title: Maturation of luteinizing hormone (gonadotropin-releasing hormone) secretion across puberty: evidence for altered regulation in obese peripubertal girls.
abstract: BACKGROUND
  Peripubertal obesity (body mass index-for-age >or= 95%) in girls is associated with hyperandrogenemia. LH likely contributes to this relationship, but overnight LH secretion in obese girls is poorly characterized.
  
  
  OBJECTIVE
  The aim of the study was to evaluate LH pulse characteristics in obese girls throughout pubertal maturation.
  
  
  METHODS
  We conducted a cross-sectional analysis.
  
  
  METHODS
  The study was performed in a general clinical research center.
  
  
  METHODS
  Eight nonobese and five obese Tanner 1-2 girls participated, as well as 32 nonobese and 12 obese Tanner 3-5 girls.
  
  
  METHODS
  Blood samples were collected every 10 min overnight (from 1900 to 0700 h).
  
  
  METHODS
  LH pulse frequency, amplitude, and mean LH were measured in three 4-h time blocks (block 1, 1900-2300 h; block 2, 2300-0300 h; and block 3, 0300-0700 h).
  
  
  RESULTS
  Tanner stage 1-2 nonobese girls demonstrated nocturnal increases of LH frequency (P < 0.01, block 1 vs. 2) and mean LH (P < 0.05, block 1 vs. 2 and 3). Obese Tanner 1-2 girls had lower 12-h LH frequency and LH amplitude (P < 0.05 for both), with no overnight changes of LH pulse parameters. Compared to normal, LH frequency was elevated in Tanner 3-5 obese girls (P < 0.01 in all blocks), whereas LH amplitude was low (P < 0.05 in all blocks). Overnight increases of LH amplitude were observed in nonobese Tanner 3-5 girls (P < 0.0001), but not in obese Tanner 3-5 girls.
  
  
  CONCLUSIONS
  Obesity in prepubertal and early pubertal girls is associated with reduced LH secretion and reduced nocturnal changes of LH. In later pubertal girls, obesity is linked with reduced LH amplitude, but elevated LH frequency; the latter may reflect effects of hyperandrogenemia.
authors.affiliation: Division of Endocrinology and Metabolism, Department of Medicine, Box 800391, University of Virginia Health System, Charlottesville, Virginia 22908, USA. cm2hq@virginia.edu
authors.forename: Christopher R
authors.initials: CR
authors.lastname: McCartney
authors.forename: Kathleen A
authors.initials: KA
authors.lastname: Prendergast
authors.forename: Susan K
authors.initials: SK
authors.lastname: Blank
authors.forename: Kristin D
authors.initials: KD
authors.lastname: Helm
authors.forename: Sandhya
authors.initials: S
authors.lastname: Chhabra
authors.forename: John C
authors.initials: JC
authors.lastname: Marshall
mesh_terms: D000293:Adolescent; D002648:Child; D003430:Cross-Sectional Studies; D004958:Estradiol / Q000097:blood; D005260:Female; D005640:Follicle Stimulating Hormone / Q000097:blood; D006801:Humans; D007986:Luteinizing Hormone / Q000378:metabolism*; D009765:Obesity / Q000378:metabolism*; D011627:Puberty / Q000378:metabolism*; D013739:Testosterone / Q000097:blood
chemical_list: D013739:Testosterone; D004958:Estradiol; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone